Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 b48b1f5fe087a773…

MALICIOUS

Office (OOXML) / .XLSX

180.8 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: 158cd0d190c5a1d093b5cd9ae33f89a2 SHA-1: dac34d6769bb1b9938790fbbd1848452939e51cb SHA-256: b48b1f5fe087a773de9ace79327c90ba001a9867cb47809728615afc51f1653d
168 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.001 Malicious Link: Malicious Link T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1059 Command and Scripting Interpreter

The file is an Excel document containing an embedded Equation Editor OLE object, which is anomalous and indicative of CVE-2018-0798. This vulnerability is known to be exploited by malware like Formbook to download and execute a second-stage payload. The ClamAV detection also confirms the presence of a Formbook downloader. No VBA or scripts were directly extracted, but the OLE object's structure strongly suggests exploitation for payload delivery.

Heuristics 5

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/oleObject1.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Embedded Equation Editor OLE data contains anomalous native stream bytes consistent with a CVE-2018-0798-style Equation Editor exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like, but it does not match the exact public matrix-overflow byte signature.
  • ClamAV: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
0e647a7534c1b6712e4a2068d41e3833a9ae1046983543054d7c174eb1eab4cf		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 4096 bytes
ooxml_oleobject_00_ole10native_00.bin
c7168ab997ebe52a973341ddef9a31fb65c2a64f81d5a2c40c259211379f29fa		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: OLe10NAtIVE 1595 bytes
emf_00.emf
5759557ba24c02cfc9afdd1c87b75705dc60fb50230d4e0551838b757016cd01		 ooxml-emf OOXML EMF part: xl/media/image7.emf 1099960 bytes

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